The present invention relates to silver halide photographic light sensitive materials achieving reduced image unevenness on scanning exposure, reduced doubling in super-fine line reproduction and reduced bleeding-fringes of black text images, and an image forming method by use thereof.
Silver halide photographic light sensitive materials (hereinafter, also simply referred to as photographic materials), which have superior characteristics such as high sensitivity and superior gradation, as compared to other print materials, are extensively employed. Recently, opportunities of treating images as digital data has rapidly increased along with enhancements in computing capability of computers and advancements in network technology. Image information digitized using a scanner can readily be edited or converted on a computer and addition of data such as characters or illustrations can also be easily performed. To reproduce such digitized image information in the form of silver halide photography, it is necessary to conduct exposure by varying the exposure amount in accordance with the image information. There are some exposing methods known in the art. Specifically, scanning exposure of photographic materials with modulated light beam, based on digital data, is advantageous in terms of exposure speed and image quality. There is generally employed a method of exposing a photographic material by a combination of raster-scanning a light beam in the horizontal direction (main scanning) and transporting the photographic material in the vertical direction at the same time to shift the raster-scanning position relatively to the photographic material (sub-scanning), and a method of arranging transport of the photographic material in the direction vertical to the exposing head in which light sources are set in array (in this case, only main scanning). However, there have been problems that periodical unevenness of densities tended to occur, corresponding to the sub-scanning pitch (in cases of an array-formed exposure head, a spacing between light sources). To perform more definite exposure, the light beam diameter is desirably decreased to enhance the picture element density. However, as the light beam diameter decreases, the scanning unevenness tends to be greater. To solve such problems, JP-A 4-249244, 5-19423 and 9-304890 (herein the term, JP-A means an unexamined, published Japanese Patent Application) disclose a technique of exposure by making the sub-scanning pitch smaller than the light beam radius to result in overlap between rasters.
Image density unevenness can be reduced by optimally setting the light beam diameter to result in overlap between rasters. In this exposure method, however, it was found that printed color tone difference was produced between superfine lines with a thickness close to the light beam diameter and a relatively broad area portions, both being substantially the same density on the computer, and the fringe of black text image tended to bleed; therefore, improvements thereof are still desired.
It is well known that in conventional printing on color paper through a processed color negative film (analog exposure), there is a relationship between gradation and sharpness of the color paper. To reduce deterioration in sharpness due to irradiation and halation, a technique of incorporating various kinds of dyes into a photographic material is common. In analog exposures, prevention of fringe bleeding of black text images and color doubling of superfine lines can be achieved by adjusting gradation of color paper and adjusting sharpness of yellow, magenta and cyan images through optimal adjustment of the dye content. In scanning exposure with light beam, however, such techniques were insufficient to solve the problems described above.
Furthermore, a number of techniques of preparation of silver halide grains have been disclosed as a method for solving problems regarding high intensity reciprocity law failure. Examples thereof include a technique of improving sensitivity by forming a high bromide silver halide phase in the vicinity of the grain surface, as described in JP-A 58-108533; a technique of incorporating fine silver bromide grains, as described in JP-A 64-6941; and a technique of allowing iridium to be contained in the high bromide localized phase. U.S. Pat. No. 5,627,020 discloses a technique of adding fine silver bromide metal-doped grains. However, these techniques describe nothing with respect to an improvement of fine line reproduction described above. JP-A 7-20596 discloses a technique of incorporating an organic desensitizer into a hydrophilic colloidal layer. This disclosure concerns improvements in handling characteristics and storage stability of roomlight handling photographic materials, but nothing was suggested therein with respect to improvement of image quality on high intensity exposure and there is no description concering addition of an organic desensitizer and effects thereof. JP-A 6-11789 discloses a technique of separately adding a chemical sensitizer. This technique, which is directed to enhancing sensitivity of silver iodobromide, teaches nothing with respect to improving image quality of high chloride silver halide photographic materials when exposed to high intensity light. U.S. Pat. No. 5,744,287 discloses a technique of controlling the gradation and fill-in maximum density so as to be within a given range. This technique, however, was proved to be insufficient to improve doubling in superfine line reproduction and fringe-bleeding of black text images. It is assumed to be due to the fact that the fill-in maximum density is a parameter calculated based on the extent of fill-in of reverse-line image portions. In such case, image portions of both sides of the reverse-line image portion are affected by multi-exposure. Contrary to that, the superfine line image portions having a width of one pixel or so, were not affected by multi-exposure.
Accordingly, an object of the present invention is to provide silver halide photographic light sensitive materials achieving reduced image unevenness on scanning exposure, reduced doubling in super fine line reproduction and reduced bleeding fringe of black text images, and an image forming method by use thereof.
The object of the invention can be accomplished by the following constitution:
1. a silver halide photographic light sensitive material comprising a support having thereon a yellow dye image forming layer, a magenta dye image forming layer and a cyan dye image forming layer, wherein when the photographic material is subjected to exposure of not more than 10xe2x88x926 sec. per pixel element and further to color developing to form yellow, magenta and cyan images, a variation at multiple exposure, based on non-multiple exposure, of an average gradation, which is a slope that connects two pints corresponding to densities of 0.5 and 1.5 on a characteristic curve of each of the yellow, magenta and cyan images, is not more than 10%;
2. the photographic material described in 1 above, wherein the photographic material satisfies the following requirements (1) and (2):
|xcex3m(Y)/xcex3m(M)xe2x88x92xcex3s(Y)/xcex3s(M)|xe2x89xa60.2xe2x80x83xe2x80x83(1)
|xcex3m(C)/xcex3m(M)xe2x88x92xcex3s(C)/xcex3s(M)|xe2x89xa60.15xe2x80x83xe2x80x83(2)
wherein xcex3m(Y), xcex3m(M) and xcex3m(C) represent an average gradation at multiple exposure of yellow, magenta and cyan images, respectively; xcex3s(Y), xcex3s(M) and xcex3s(C) represent an average gradation at non-multiple exposure of yellow, magenta and cyan images, respectively;
3. the photographic material described in 1 above, wherein the photographic material satisfies the following requirements (3) and (4):
|Dl(Y)/D1(M)xe2x88x92Ds(Y)/Ds(M)|xe2x89xa60.5xe2x80x83xe2x80x83(3)
|Dl(C)/D1(M)xe2x88x92Ds(C)/Ds(M)|xe2x89xa60.5xe2x80x83xe2x80x83(4)
wherein Dl(Y), Dl(M) and Dl(C) represent a reflection density of a square portion with an area of (beam diameterxc3x971000)2, obtained when subjected to scanning exposure in the maximum exposure amount and at 25% of overlap between light beam rasters with respect to yellow, magenta and cyan images, respectively, and Ds(Y), Ds(M) and Ds(C) represent a reflection density of a square portion with an area of (beam diameterxc3x972)2 when subjected to scanning exposure in the maximum exposure amount and at 25% of overlap between light beam rasters with respect to yellow, magenta and cyan images, respectively;
4. the photographic material described in any of 1 to 3, wherein the yellow dye image forming layer, magenta dye image forming layer and cyan dye image forming layer each comprises light sensitive silver halide grains having a chloride content of not less than 95 mol %;
5. An image forming method comprising:
subjecting the photographic material as described in any of 1 to 4 above to scanning exposure with a light beam modulated based on image information for an exposure time of not more than 10xe2x88x926 sec per pixel and then
subjecting the exposed photographic material to color processing; and
6. the method described in 5 above, wherein the total time from completion of exposure and to start of color processing is not more than 30 sec.